/* Marine Engineering & Tribology Group — site stylesheet
   Plain CSS, no build step, no external fonts or CDNs (works offline). */

:root {
  --navy: #0a2540;
  --navy-soft: #14395c;
  --teal: #0e7c86;
  --teal-dark: #0a5b63;
  --amber: #c8853a;
  --ink: #1c2430;
  --muted: #5a6a7a;
  --line: #dfe5ec;
  --bg: #f6f7f9;
  --card: #ffffff;
  --shadow: 0 1px 2px rgba(10, 37, 64, .06), 0 8px 24px rgba(10, 37, 64, .07);
  --radius: 10px;
  --wrap: 1160px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font: 16px/1.62 -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  -webkit-font-smoothing: antialiased;
}

img { max-width: 100%; height: auto; display: block; }
a { color: var(--teal-dark); text-decoration: none; }
a:hover { text-decoration: underline; }

h1, h2, h3, h4 { color: var(--navy); line-height: 1.22; margin: 0 0 .5em; }
h1 { font-size: clamp(1.85rem, 1.2rem + 2.2vw, 2.7rem); letter-spacing: -.01em; }
h2 { font-size: clamp(1.4rem, 1.1rem + 1.1vw, 1.9rem); margin-top: 1.6em; }
h3 { font-size: 1.12rem; }
p  { margin: 0 0 1em; }

.wrap { width: 100%; max-width: var(--wrap); margin: 0 auto; padding: 0 20px; }
.skip { position: absolute; left: -9999px; }
.skip:focus { left: 8px; top: 8px; background: #fff; padding: 8px 12px; z-index: 50; }

/* ---------- header ---------- */
.site-header {
  position: sticky; top: 0; z-index: 20;
  background: rgba(255, 255, 255, .96);
  border-bottom: 1px solid var(--line);
}
.header-inner { display: flex; align-items: center; gap: 18px; min-height: 68px; }
.brand { display: flex; align-items: center; gap: 12px; color: inherit; }
.brand:hover { text-decoration: none; }
.brand-mark { display: grid; place-items: center; width: 40px; height: 40px; border-radius: 50%; background: var(--navy); color: #fff; flex: 0 0 40px; }
.brand-text { display: flex; flex-direction: column; line-height: 1.25; }
.brand-text strong { color: var(--navy); font-size: .98rem; }
.brand-text small { color: var(--muted); font-size: .74rem; letter-spacing: .02em; }

.site-nav { margin-left: auto; display: flex; flex-wrap: wrap; gap: 2px; }
.site-nav a { padding: 8px 11px; border-radius: 6px; color: var(--navy-soft); font-size: .9rem; font-weight: 500; white-space: nowrap; }
.site-nav a:hover { background: #eef2f6; text-decoration: none; }
.site-nav a[aria-current="page"] { background: var(--navy); color: #fff; }

.nav-toggle {
  display: none; margin-left: auto; padding: 8px 12px; font: inherit; font-size: .9rem;
  color: var(--navy); background: #fff; border: 1px solid var(--line); border-radius: 6px; cursor: pointer;
}

/* ---------- hero ---------- */
.hero { position: relative; color: #fff; background: var(--navy); overflow: hidden; }
.hero img.hero-img { position: absolute; inset: 0; width: 100%; height: 100%; object-fit: cover; opacity: .34; }
.hero::after { content: ""; position: absolute; inset: 0; background: linear-gradient(105deg, rgba(10, 37, 64, .93) 0%, rgba(10, 37, 64, .72) 45%, rgba(14, 124, 134, .55) 100%); }
.hero-inner { position: relative; z-index: 2; padding: clamp(48px, 8vw, 96px) 0; max-width: 800px; }
.hero h1 { color: #fff; margin-bottom: .35em; }
.hero p.lead { font-size: 1.08rem; color: #dbe6f0; max-width: 62ch; }
.hero .eyebrow { text-transform: uppercase; letter-spacing: .16em; font-size: .72rem; color: #8fd3da; margin-bottom: 10px; }
.hero .btn-row { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 26px; }

.btn { display: inline-block; padding: 11px 20px; border-radius: 7px; font-weight: 600; font-size: .94rem; border: 1px solid transparent; }
.btn:hover { text-decoration: none; }
.btn-primary { background: var(--teal); color: #fff; }
.btn-primary:hover { background: var(--teal-dark); }
.btn-ghost { border-color: rgba(255, 255, 255, .55); color: #fff; }
.btn-ghost:hover { background: rgba(255, 255, 255, .12); }

/* ---------- inner page head ---------- */
.page-head { background: var(--navy); color: #fff; padding: clamp(34px, 5vw, 58px) 0; }
.page-head h1 { color: #fff; margin-bottom: .25em; }
.page-head p { color: #cddced; max-width: 72ch; margin: 0; }
.crumbs { font-size: .8rem; color: #9fb6cd; margin-bottom: 12px; }
.crumbs a { color: #bcd9de; }

/* ---------- sections & layout ---------- */
.section { padding: clamp(38px, 5vw, 64px) 0; }
.section.tight { padding: clamp(26px, 3.5vw, 40px) 0; }
.section.alt { background: #fff; border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.section-head { max-width: 78ch; margin-bottom: 28px; }
.section-head p { color: var(--muted); }

.grid { display: grid; gap: 22px; }
.grid.cols-2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid.cols-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid.cols-4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }

.card { background: var(--card); border: 1px solid var(--line); border-radius: var(--radius); box-shadow: var(--shadow); overflow: hidden; }
.card-body { padding: 20px 22px; }
.card h3 { margin-top: 0; }
.card p:last-child { margin-bottom: 0; }
.card img { border-bottom: 1px solid var(--line); }

.split { display: grid; grid-template-columns: minmax(0, 1.05fr) minmax(0, 1fr); gap: 32px; align-items: center; }
.split.reverse .split-media { order: 2; }
.split-media img { border-radius: var(--radius); border: 1px solid var(--line); box-shadow: var(--shadow); }
figure { margin: 0; }
figure figcaption, .split figcaption { color: var(--muted); font-size: .82rem; margin-top: 8px; }

/* ---------- stat strip ---------- */
.stats { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 1px; background: var(--line); border: 1px solid var(--line); border-radius: var(--radius); overflow: hidden; }
.stat { background: #fff; padding: 20px; text-align: center; }
.stat b { display: block; font-size: 1.7rem; color: var(--navy); line-height: 1.1; }
.stat span { color: var(--muted); font-size: .84rem; }

/* ---------- lists, tables, tags ---------- */
ul.clean { list-style: none; padding: 0; margin: 0; }
ul.clean li { padding: 9px 0 9px 24px; position: relative; border-bottom: 1px dashed var(--line); }
ul.clean li:last-child { border-bottom: 0; }
ul.clean li::before { content: ""; position: absolute; left: 4px; top: 17px; width: 8px; height: 8px; border-radius: 2px; background: var(--teal); }

ul.ticks { list-style: none; padding: 0; margin: 0 0 1em; }
ul.ticks li { position: relative; padding: 4px 0 4px 26px; }
ul.ticks li::before { content: "\2713"; position: absolute; left: 4px; color: var(--teal); font-weight: 700; }

table { width: 100%; border-collapse: collapse; background: #fff; border: 1px solid var(--line); border-radius: var(--radius); overflow: hidden; }
th, td { text-align: left; padding: 12px 14px; border-bottom: 1px solid var(--line); vertical-align: top; font-size: .92rem; }
thead th { background: #eef2f6; color: var(--navy); font-size: .8rem; text-transform: uppercase; letter-spacing: .06em; }
tbody tr:last-child td { border-bottom: 0; }

.tags { display: flex; flex-wrap: wrap; gap: 8px; padding: 0; margin: 0; list-style: none; }
.tags li { background: #eaf3f4; color: var(--teal-dark); border-radius: 999px; padding: 5px 12px; font-size: .82rem; }

.pub { border-left: 3px solid var(--teal); padding: 2px 0 2px 16px; margin: 0 0 18px; }
.pub .venue { color: var(--muted); font-size: .88rem; }
.pub .meta { color: var(--amber); font-size: .8rem; font-weight: 600; letter-spacing: .03em; }

.note { background: #fff8ec; border: 1px solid #f0dcbb; border-left: 4px solid var(--amber); border-radius: 8px; padding: 16px 18px; }
.note p:last-child { margin-bottom: 0; }
.quote { border-left: 4px solid var(--navy); padding: 4px 0 4px 18px; font-size: 1.04rem; color: var(--navy-soft); }

/* ---------- footer ---------- */
.site-footer { background: var(--navy); color: #c8d6e5; }
.footer-grid { display: grid; grid-template-columns: 1.4fr 1fr 1.2fr; gap: 30px; padding: 46px 20px; }
.site-footer h3 { color: #fff; font-size: .95rem; letter-spacing: .04em; text-transform: uppercase; }
.site-footer a { color: #9fd6dc; }
.site-footer ul { list-style: none; padding: 0; margin: 0; }
.site-footer li { padding: 3px 0; font-size: .92rem; }
.footer-bottom { border-top: 1px solid rgba(255, 255, 255, .14); padding: 16px 20px 26px; font-size: .82rem; color: #93a7bb; }
.footer-bottom p { margin: 0; }

/* ---------- responsive ---------- */
@media (max-width: 1020px) {
  .grid.cols-4, .grid.cols-3 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .footer-grid { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 760px) {
  .nav-toggle { display: block; }
  .site-nav { display: none; width: 100%; margin: 0 0 12px; flex-direction: column; border-top: 1px solid var(--line); padding-top: 8px; }
  .site-nav.open { display: flex; }
  .site-nav a { padding: 10px 12px; }
  .header-inner { flex-wrap: wrap; padding: 10px 0; }
  .grid.cols-2, .grid.cols-3, .grid.cols-4 { grid-template-columns: 1fr; }
  .split { grid-template-columns: 1fr; gap: 22px; }
  .split.reverse .split-media { order: 0; }
  .stats { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .footer-grid { grid-template-columns: 1fr; gap: 22px; }
}

@media print {
  .site-header, .site-footer, .hero .btn-row { display: none; }
  body { background: #fff; }
}